Field of the Invention
The present invention relates to a fuel cell system and a control method of the same.
Background Art
Hitherto, a fuel cell system provided with a fuel cell adapted to receive the supply of reactant gases (a fuel gas and an oxidizing gas) to generate power has been proposed and in practical use. A fuel cell is a power generation system which oxidizes a fuel by an electrochemical process so as to directly convert the energy released by the oxidation reaction into electric energy. When power is generated by such a fuel cell system, water is generated inside the fuel cell by the electrochemical reaction. There are cases where the generated water is retained in a reactant gas flow path in the fuel cell, blocking the flows of the reactant gases. Further, when the fuel cell system is operated in a low temperature environment of a freezing point or the like, the water remaining in the electrodes (a catalyst layer or a diffusion layer) of the fuel cell freezes, causing marked deterioration in the startup performance thereof.
Currently, in order to solve various problems attributable to the water generated in a fuel cell, there has been proposed a technology for supplying dry oxygen or dry hydrogen to a reactant gas flow path while the operation of a fuel cell is stopped, thereby carrying out a scavenging treatment to reduce the water in a gas flow path in the fuel cell or the moisture on a valve and the like of a fuel cell system (refer to, for example, Patent Document 1). According to the technology described in Patent Document 1, the timing of a scavenging treatment is supposed to be adjustable according to an outside air temperature or a fuel cell temperature.